In search of a terrorist nuclear bomb, the federal government since 9/11 has run a far-reaching, top secret program to monitor radiation levels at over a hundred Muslim sites in the Washington, D.C., area, including mosques, homes, businesses, and warehouses, plus similar sites in at least five other cities, U.S. News has learned. In numerous cases, the monitoring required investigators to go on to the property under surveillance, although no search warrants or court orders were ever obtained, according to those with knowledge of the program. Some participants were threatened with loss of their jobs when they questioned the legality of the operation, according to these accounts. Federal officials familiar with the program maintain that warrants are unneeded for the kind of radiation sampling the operation entails, but some legal scholars disagree. . . . The nuclear surveillance program began in early 2002 and has been run by the FBI and the Department of Energy's Nuclear Emergency Support Team (NEST). Two individuals, who declined to be named because the program is highly classified, spoke to U.S. News because of their concerns about the legality of the program. At its peak, they say, the effort involved three vehicles in Washington, D.C., monitoring 120 sites per day, nearly all of them Muslim targets drawn up by the FBI. For some ten months, officials conducted daily monitoring, and they have resumed daily checks during periods of high threat. The program has also operated in at least five other cities when threat levels there have risen: Chicago, Detroit, Las Vegas, New York, and Seattle.

Among the interesting Fourth Amendment questions here is whether this monitoring is distinguishable from Kyllo v. United States. For example, is measuring ambient gamma rays different from measuring infrared radiation emanating from a specific surface? Are Geiger counters (or whatever tool they used to measure radiation) in "general public use"? And does Kyllo, which was focused on the case of a private home, also apply to mosques, businesses, and warehouses?

I'm scheduled to go to the ABC News studio in a bit to discuss some of these issues; if it works out, a blurb or two on the legal issues might make it on to World News Tonight. (BTW, what's with all the high-tech surveillance stories breaking when I'm supposed to be grading exams? Bad timing.)

(1) The argument that the police can't aim radiation surveillance devices at homes (and likely businesses, mosques, and the like) without a warrant is a nontrivial one: It's basically Kyllo v. United States (no aiming heat sensors at homes without a warrant) meets Mincey v. Arizona (no special Fourth Amendment exceptions for investigations of very serious crimes). I discuss this in this Slate piece from 2002.

My ultimate conclusion is that such radiation surveillance from outside the buildings should be constitutional, because what's an "unreasonable search" when looking for drugs (or even for evidence of murder) becomes reasonable when looking for radiation weapons: "[F]inding dirty bombs must simply be different from fighting normal crime. Searches for weapons of mass destruction can't be treated like searches for marijuana-growing devices or even for murder weapons." Others have argued that it might be constitutional for another reason -- searches that are likely to reveal only evidence of contraband (which, the argument would go, includes searches for radioactive materials but not for heat sources) don't invade any reasonable expectation of privacy; I'm not as wild about that theory, but I agree with its bottom line. Nonetheless, I think the Slate piece may help explain the nature of the argument that such searches are unconstitutional.

(2) Orin points out that "In numerous cases, the monitoring required investigators to go on to the property under surveillance, although no search warrants or court orders were ever obtained, according to those with knowledge of the program." I want to caution people against assuming that going onto the property under surveillance without a warrant is per se unconstitutional under existing law. There are various reasons why entering the property wouldn't itself be treated as an unconstitutional search, for instance if the parts of the property that they entered was generally open to the public, or if the property was the urban equivalent of "open fields" as opposed to the inside of someone's building (or the "curtilage" of that building).

Some of these doctrines are quite complex and unsettled, and I don't want to go into them in detail here; and I also want to stress that even if entering the property wasn't a search, doing some things on that property (perhaps including measuring radiation, or perhaps not, see item 1 above) may well be a search. But people should realize that whether "go[ing] on to the property under surveillance" is unconstitutional without a warrant is a difficult question.

The "Special Needs" Exception:
In his Slate piece from 2002, Eugene argues that checking radiation levels to avoid a nuclear attack is "just different" from using an infrared device in a routine criminal case. He writes:

Sure, normally the Fourth Amendment applies equally to all serious crimes, and that's normally right. But finding dirty bombs must simply be different from fighting normal crime. Searches for weapons of mass destruction can't be treated like searches for marijuana-growing devices or even for murder weapons. The Fourth Amendment, by its terms, only bans "unreasonable searches and seizures"—and it cannot be unreasonable to examine homes with Geiger counters in order to prevent a city from being rendered uninhabitable by an enemy bombing. Protecting people's privacy is important, and so is constraining government power. But sometimes we need extraordinary government power to protect against extraordinary threat.

I just thought I would add that there is a Fourth Amendment doctrine that recognizes Eugene's intuition: the "special needs" exception. The idea behind the "special needs" exception is that the government has lots of legitimate interests beyond collecting evidence in criminal cases. When government agents are pursuing those other interests, the warrant requirement is relaxed and the overall requirement is reasonableness. There are a bunch of Supreme Court cases on this doctrine, starting (I believe) with Camara v. Municipal Court in 1967 and receiving more formal attention in cases like O'Connor v. Ortega.